This application requests funds to purchase a biocontained Amnis Imagestream 100 Imaging Cytometer. This application is a joint submission of the CBR Institute for Biomedical Research and the Center for AIDS Research at Harvard. It will be a Core resource for AIDS researchers at Harvard. The instrument will be placed in a biosafety cabinet in a BL2+ laboratory so as to be useful for analysis of cells infected with HIV, SIV or other pathogens requiring BL2+ safety handling. The imaging cytometer is a cutting edge new hybrid instrument that combines the best features of flow cytometry with microscopic imaging. This will represent a unique resource, since no imaging cytometry is currently available at the Harvard Medical School or its affiliated institutions. The imaging cytometer allows investigators to collect brightfield, darkfield and up to four fluorescent images for each cell at a rate of 100 cells/second. Imaging software allows the quantification of morphological features and subcellular fluorescence staining patterns in subpopulations of cells. Because thousands of cells are analyzed at one time, this new technology provides objective and statistically significant assessment that bypasses the limitations of conventional microscopy that can only analyze small numbers of cells that may be inadvertently selected in a biased manner by the observer. Moreover, the gating features of the instrument allow users to characterize the properties of rare cells, comprising fewer than a fraction of a percent of cells in mixed populations, and to harvest these cells for further in vitro characterization. These features will enable analysis of antigen-specific lymphocytes, rare infected cells or hematopoietic cells in the blood without introducing artifacts that arise from selection or cell culture and expansion. The new imaging cytometer will provide a much-needed and valuable research tool for studying subcellular changes in molecules and for studying the properties of lymphocytes responding to infection, infected cells and hematopoietic progenitor cells. These talented researchers will also be able to define the best ways that this new technology can be applied to solve biomedical research problems. The imaging cytometer will support innovative research studies in AIDS, tuberculosis and other infectious diseases, stem cell biology, immunology, hematopoiesis and oncogenesis. It will guide efforts for developing effective vaccines and immunotherapies and drug therapies for infection and cancer. [unreadable] [unreadable] [unreadable]